Crystal-field effects on the crossover temperature ofSm3+magnetization in magnetically ordered samarium compounds

White and Van Vleck have shown that in magnetically ordered samarium compounds, where the ${\mathrm{Sm}}^{3+}$ ion can be considered as a "free" ion, the exchange field acting alone produces a sign change or a crossover in ${\mathrm{Sm}}^{3+}$ magnetization at a temperature of about 300 K. This result is a consequence of the admixture of $J=\frac{7}{2}$ level into $J=\frac{5}{2}$ level of the ${\mathrm{Sm}}^{3+}$ ion by exchange fields. We show that the crystal-field interaction strongly influences the crossover temperature and the magnitude of ${\mathrm{Sm}}^{3+}$ magnetization. Samarium iron garnet is one of the systems where a crossover temperature has been observed.